he Universal Serial Bus, more commonly known as USB, is a relatively new system for attaching keyboards, mice, printers, scanners, microphones, and lots of other kinds of devices to desktop and laptop computers.

USB is supposed to make computers easier to use, less expensive, and more flexible. USB is also supposed to end the second-class status of Macintosh users, since USB devices are theoretically compatible between Macs and PCs.

The heart of USB is the flat, rectangular connector that is on the backs of many laptop and desktop computers sold today. This connector supplies both power and data to peripherals. If you want to attach a USB scanner to your laptop, you just plug it in. The Windows 98 operating system is supposed to automatically recognize the scanner, load the driver, and let you use the device - all without having to reboot.

Most new computers today come with two USB connectors. If you want more, you can buy a USB hub. Some hubs also have their own serial ports or printer ports, allowing you to connect older modems and printers to the high-performance USB system. If you have an older computer, fret not: You can buy a plug-in USB adapter card for less than $50.

Unfortunately, while USB is off to a pretty good start, it still has a lot of growing up to do. Surprisingly, that's because the same companies that have been quick to adopt USB have been slow to give the technology their full support.

Apple Computer has been one of the most enthusiastic adopters of USB, largely because it has the most to gain. When Apple introduced the iMac, the new computer came with a USB keyboard and a USB mouse. What Apple left out was the floppy disk. The company told people who wanted a floppy to go out and buy one that could plug into the USB port. A lot of people said that Apple really blundered, because there weren't actually any USB floppy disk drives on the market when Apple first launched its iMac.

But what Apple actually did was jump-start the market, by creating a class of users that were desperate for the technology. Today you can see the result: There are many USB floppy drives and Zip drives on the market from a variety of companies. Shipping the iMac without a floppy revitalized Apple's third-party suppliers.

Things haven't been going as well in the PC world. In principle, USB allows computer makers to eliminate the confusing collection of sockets that are on the back of most PCs and instead have a neat little row of USB connectors. In theory, this would let computer makers simplify their production lines and thus cut prices.

But most PC makers aren't looking for ways to cut prices. Instead, they are looking for techniques to justify higher prices and profit margins in an increasingly competitive environment. So PC vendors simply added two USB ports to their standard port collection.

Because no PC vendor jumped whole-hog to USB, the technology has spread more slowly in the PC world. Today you can buy some USB devices, but the majorityof peripherals sold for PC users are not USB-compatible.

One really neat USB device that I've seen is a microphone made by Telex anddesigned for use with PC speech-recognition systems, such as Dragon Systems'sNaturally Speaking. One of the big problems that companies like Dragon have hadis that PCs don't have very good audio recording subsystems. The electronics that digitize the microphone pick up lots ofcracks and pops. The noise makes speech recognition much more difficult.

The Telex USB microphone gets around this problem by digitizing the soundoutside the computer and sending it to the PC in digital form, through the USBinterface. This is especially important for laptop uses, since laptop PCstypically have even worse sound systems than desktop units.

Dragon Systems sells the Telex microphone under the name Dragon NaturallyClear USB System H100 at a list price of $79.95. I haven't seen it in stores, but you can buy it from Dragon's Web site at www.dragonsys.com.

Another interesting USB device is Visioneer's new PaperPort Strobe Pro ($200). Visioneer's scanner can connect to a PC through either the USB port or through a standard serial port. The advantage of running the Visioneer off the USB port is that it is faster, and you don't need an external power supply.

Unfortunately, Visioneer's scanner also demonstrates just how much work is needed for PC firms to realize USB's full potential. Even though data travels over USB more than 10 times faster than over a high-speed serial port, Visioneer's Strobe Pro scans pages somewhat slower than the Strobe scans using its high-speed parallel interface.

Another problem has been software compatibility. Visioneer's 6.0 PaperPort desktop software won't work with its top-of-the-line USB scanner. Visioneer knows about the problem and is working on it. (An experimental driver is available that fixes the problem. Contact Visioneer for details.)

Finally, while Visioneer is selling a Macintosh version of its USB Strobe Pro scanner, it's priced at $249.99. This misses the point of USB entirely.